In the case of air springs for passenger vehicle use, the use of rolling bellows with double rolling folds is described, for example, to EP 1 239 181 A2. However, in the embodiment described there, only a rolling piston for the lower rolling fold is provided. The upper rolling fold rests in a cutout on the cover of the air spring and has the single purpose of permitting the air spring to be pivotable with respect to the shock absorber which is connected thereto.
A further possibility in which an air spring is used with double rolling folds is dealt with in EP 1 171 722 B1. In the embodiment shown, the lower rolling fold rolls on a cylindrical rolling piston, whereas the upper rolling fold can carry out a small rolling movement on a conically extending rolling surface on the cover of the air spring. This arrangement of piston and cover and also of the double rolling fold is intended to result in an improvement in the comfort properties when an air spring is used.
The use of two opposite pistons and of a rolling bellows with double rolling folds is shown in FIG. 9 of DE 1 107 030. Two identically sized rolling pistons for the rolling folds are provided, and therefore this embodiment can only be used for spring purposes. This statement also applies to the embodiment in U.S. Pat. No. 3,876,193, in which the rolling folds are used solely for spring purposes. The two rolling folds move simultaneously during the cushioning operation.
Finally, U.S. Pat. No. 4,718,650 describes an air spring which requires very little space for the deflection operation, since the piston wall of the lower piston is fittable telescopically into a clearance on the upper piston when the air spring is compressed in the minimal position thereof. The air spring can be extended in such a manner that the lower rolling fold is completely detached from the lower rolling piston and the upper rolling fold is also pulled out of the receptacle. However, that part of the rolling bellows which forms the upper rolling fold is provided with an enclosure which prevents the upper rolling fold from rolling back into the starting position thereof. As claimed in the present construction, a reduction in pressure in the compressed air space alone cannot result in the rolling fold returning into the starting position thereof. Only the upper edge of the lower rolling piston can push the upper rolling fold back, but this does not lead to complete contact with the rolling fold; instead, air spaces remain. This construction is consequently not suitable for realizing a smooth execution of a lifting operation.